Organic light emitting diodes (OLEDs) are light emitting diodes (LEDs) incorporating an organic material as the light emitting material. OLEDs are an active area of research for solid state lighting and have many potential advantages over current inorganic material-based LEDs. There are many different designs for OLEDs, but one limitation they all suffer from is that it can be challenging to extract significant amounts of light from the device. Because the emission layers are typically made from high refractive index materials, a high proportion of light is trapped within the device, thus lowering the overall efficiency. The typical way to improve light extraction from the substrate is to place a diffusive structure in the front to extract the trapped (TIR, total internal reflection) light. However, this method only gives moderate improvements. There continues to be a need to improve the amount of light efficiently extracted from OLED devices.